Story Highlights

If you look hard enough, there are signs that Americans are finally getting the message about how heavy and out-of-shape they are.

Consumption of diet drinks is increasing, and the calories Americans consume from regular sodas are on the way down.

More than half of Americans (55%) say they are trying to drop some weight, up significantly from 43% in 2011, according to a recent survey conducted for the International Food Information Council Foundation.

But while the concern about obesity may have hit the national consciousness, it hasn't really shown up on the bathroom scale for most Americans yet.

The reality is that the nation is now entering a fourth decade of weight gain. The obesity rate — those who are 30 or more pounds over a healthy weight — stayed fairly level at 15% from 1960 to 1980.

Since then it climbed to 36% in 2010, an all-time high. If it continues to grow, about 42% of Americans may end up obese by 2030, according to a projection from researchers with RTI International, a non-profit organization in North Carolina's Research Triangle Park.

"If you go with the flow in America today, you will end up overweight or obese, as two-thirds of all adults do," says Thomas Frieden, director of the Centers for Disease Control and Prevention.

The project offers a way for family members to get in shape together.(Photo: USA TODAY)

Obesity is "one of the few things that has gotten worse quickly," he says. "It really is a very serious health problem."

Obesity takes a huge toll on people's health. "Obesity is not just a cosmetic problem. It contributes to a long list of serious health problems — diabetes, cardiovascular disease, liver problems, degenerative joint disease, and even cancer," says Francis Collins, director of the National Institutes of Health.

Those extra pounds rack up billions of dollars in weight-related medical bills. It costs about $1,400 more a year to treat an obese patient compared with a person at a healthy weight, Frieden says. It costs $6,600 more a year to treat someone with diabetes, he says.

So where did we go wrong, and what will it take to reverse the trend?

National obesity experts say that over the past three decades, Americans' eating habits have changed dramatically. Food marketers, manufacturers and restaurants are selling us more food in bigger portions — and we're happy to wolf down much more than we used to.

The culprit behind the epidemic is that "we are eating significantly more calories now" than 30 years ago, Frieden says. "At its most basic level, obesity is a problem of calories."

A number of observers cite a litany of changes that have reshaped food consumption: Fast-food chains are pushing bigger hamburgers, beverages and servings of french fries; restaurants have doubled the portion sizes of their meals.

Meanwhile, jobs put fewer physical demands on workers, and physical education has been squeezed out of many schools.

These and many other changes, big and small, have led to "the perfect storm that has caused the obesity rate we have today," says James Hill, executive director of the Anschutz Health and Wellness Center at University of Colorado.

States, cities and communities have taken action across the country to reverse the trend. Schools are being pushed to offer healthier foods to kids, and programs such as first lady Michelle Obama's Let's Move are trying to get them to exercise more.

In one of the most high-profile efforts, New York City is putting a 16-ounce cap on sweetened bottled drinks and fountain beverages sold at city restaurants, delis, movie theaters, sports venues and street carts.

Though many people consider sugar one of the big villains, it doesn't bear sole responsibility, Hill says. "I'm not here to defend sugar," but the causes of obesity are more complex than just sugar intake, he says. Many Americans are following high-fat, high-calorie diets, and they are not moving nearly as much as they should, he says.

"There's a lot we don't know about obesity," Frieden adds. "I don't think we can blame our genes, because we have basically the same genetic makeup we had 40 years ago. It's not that we have gotten less self-disciplined. What has happened is the structure of our society has changed in ways that make it difficult to maintain a healthy weight."

Surrounded by food

So how much more are we eating?

Research suggests different amounts. It's in the "ballpark" of maybe 200 to 400 more calories a day than 20 years or so ago, says Marion Nestle, a nutrition professor at New York University and co-author of Why Calories Count.

Collins says it's not hard to consume just 100 calories more each day than you need, but for an average person that would result in a 10-pound weight gain over a year.

Where people eat has changed significantly as well. They now gobble meals and snacks at the desk, in the car, standing up, in food courts at malls, in gas stations, says Kelly Brownell, director of Yale University's Rudd Center for Food Policy and Obesity. There are more grab-and-go foods everywhere you turn.

"People tend to consume whatever they find in a bag, bottle or box, and the sizes of all these things have increased dramatically," Brownell says.

Lisa Young, an adjunct professor of nutrition at New York University and author of The Portion Teller Plan, has spent years studying the trends. The serving sizes of foods sold in stores and restaurants — from candy bars to burgers and sodas — have become much bigger since the early 1980s, Young says.

Over the past three decades, food companies and restaurants competed by offering consumers larger portions and thus more calories for their money. And studies show that when you give people more food, they consume more, Young says.

"Portion sizes at restaurants are marketed in a way that makes you want to supersize for just pennies more, when in reality, it's adding on hundreds more calories and sometimes even thousands," says Heather Burczynski, 37, an administrative assistant in Nashville.

Adds Nestle, "There were enormous changes, and of course, they happened without anyone realizing it because they came in one by one."

Nestle and Young are convinced that these bigger portions account for much of the weight gain over the past 30 years. "I don't think you need anything more than larger portions to account for the increase in obesity. It is sufficient," Nestle says. "Larger portions have more calories."

But Sean McBride of the Grocery Manufacturers Association, a group that represents the food and beverage industry, says its member companies "want to make sure they are providing consumers with the product choices they need for their changing preferences and lifestyles."

"Parents don't want to be told what they should or shouldn't buy, they want information and options, and that's what we're working to provide them," says Susan Neely, president of the American Beverage Association.

Registered dietitian Joy Dubost, director of nutrition for the National Restaurant Association, adds: "Just to blame obesity on portion size is shortsighted. It gives people a false sense of security that if they just cut portions they are going to lose weight.

"It's about how much you eat and how much you burn. The exercise portion of the equation has been missed in the debate of what caused obesity."

It's not only food that is to blame, Hill agrees. "If we were as active as we were in the 1950s, I don't think we'd have nearly the problem with obesity, even with our current food environment."

Kevin Fowler, 53, of Farmington, Minn., a safety director at an electric company, has seen the problem even in the way kids get to burn off energy: "I don't see the all-day-long kid-organized pickup baseball and football games at the park anymore like we used to do as kids. Those kinds of opportunities to be active every day not only gave us great memories, but they helped to develop habits that can last a lifetime. Instead, kids' sports today are too structured, too specialized and too expensive for a lot of families."

More sitting, less moving

Tim Church, director of preventive-medicine research at the Pennington Biomedical Research Center in Baton Rouge, points out that work-related physical activity also has decreased dramatically over the past 40 years.

He and colleagues analyzed data from the U.S. Bureau of Labor Statistics from the 1960s to 2008 and found that today's workers are burning an average of 120 to 140 fewer calories a day at their jobs than workers in the 1960s. Men burn an average 142 fewer calories a day at work; women burn an average 124.

The lower activity level is the result of a dramatic drop in the number of active jobs in manufacturing and farming and an increase in office jobs that are mostly sedentary, Church says. "We have transitioned from the 1960s, when most Americans were essentially exercising at work to now, where almost everyone sits the majority of the workday."

In a recent government study, about 48% of people in 2010 said they were meeting the government's physical activity guidelines — at least 150 minutes of moderate-intensity aerobic activity, such as brisk walking, a week. The finding was based on their self-reports about how active they are. But researchers with the National Cancer Institute, using actual motion sensors, found that less than 5% of adults in this USA get at least 30 minutes a day of moderate intensity physical activity in bouts of at least 10 minutes.

"I am convinced that activity levels have declined, and personally I am convinced that declining physical activity may be the key factor underlying the obesity epidemic," says Russell Pate, an exercise researcher at the University of South Carolina.

Hill says society has "engineered activity out of our lives. How many remote controls do you have in your house? Most people are so sedentary that their energy balance regulation system doesn't work very well."

"Now we know that being sedentary is another risk factor for premature death," Hill says. In one recent study, Pennington researchers found that if most people spent less than three hours a day sitting, it would add two years to the average life expectancy in the USA. Scientists believe that what's called "sitting disease" is a risk factor for early death, on par with smoking

Says Hill: "It's a fallacy to think you could change one thing and fix obesity. Many things need to change to turn this problem around."